JP7059967B2 - Single crystal growth device and single crystal growth method - Google Patents

Description

According to the present invention, in the Czochralski method (CZ method), a single crystal growing apparatus and a single crystal growing method which are less likely to cause dislocations and are energy-saving while safely strengthening crystal cooling without crystal collapse. Regarding.

In the CZ method, the crystal is cooled in order to increase the growth rate to improve productivity, and to improve the quality by suppressing the growth of crystal defects and the diffusion of point defects. The technology to do is very important. In order to cool the crystal, a method of absorbing the radiant heat from the crystal into a forcedly cooled object such as a chamber is effective.

In Patent Document 1, the opening area of the rectifying cylinder is increased and the heat of the single crystal is efficiently radiated to the ceiling of the main chamber to cool the crystal. In such a cooling method, it is important not to place an obstacle such as a graphite material or a heat insulating material that blocks radiation between the water cooling chamber that cools the single crystal being grown. However, the fact that no graphite material or heat insulating material is installed means that the water-cooled chamber receives radiation from raw material melts other than crystals (hereinafter sometimes referred to as "melt") and heaters without blocking, resulting in energy loss. There was a problem that it was big.

As a means capable of reducing this energy loss, Patent Document 2 discloses a technique including a crucible upper heat insulating member, a crucible outer heat insulating member, a crucible inner heat insulating member, and a heat insulating member. By using this technique, it is possible to maintain the heat retention of the liquid surface of the raw material melt, and it is possible to suppress dislocation due to solidification or the like. However, in this technique, there is an obstacle called a heat insulating material that blocks radiation between the heat generating portion and the water cooling chamber. Moreover, since the heat insulating material enhances the heat retention in the furnace, the temperature gradient in the furnace surrounded by the heat insulating material is difficult to form, which is completely disadvantageous in terms of crystal cooling. Although it has been strengthened, it has the problem of slowing down the growth rate.

As another method of crystal cooling, Patent Documents 3 and 4 disclose a cooling cylinder forcibly cooled by a cooling medium and a cooling auxiliary member extending downward thereof. In this method, since the cooling cylinder responsible for cooling is located around the crystal, it is possible to directly cool the crystal without blocking radiation. Further, Patent Document 5 discloses a technique of fitting a cooling auxiliary cylinder that has a cut penetrating in the axial direction and extends toward the surface of the raw material melt inside the cooling cylinder. By mounting the cooling auxiliary cylinder having a cut penetrating in the axial direction in this way, the cooling auxiliary cylinder is brought into close contact with the cooling auxiliary cylinder. Furthermore, when a graphite material is used for the cooling auxiliary cylinder, the graphite material absorbs the heat of the crystal well because of its high radiation conductivity, and the absorbed heat can be better transferred to the cooling cylinder which is in close contact with it because of its high thermal conductivity. Moreover, since it can be highly purified, it is a very effective means because it does not contaminate the crystals.

The technique of Patent Document 5 can absorb heat more efficiently than the technique disclosed in Patent Documents 6 and 7 in which a metal cooling cylinder having a low emissivity (high reflectance) is simply extended to near the surface of the molten metal. Further, since it is not necessary to blacken the inner surface of the cooling cylinder in order to improve the emissivity described in claim 11 of the cited document 6, there is no concern of contaminating the crystals.

Japanese Unexamined Patent Publication No. 2010-013300 Japanese Unexamined Patent Publication No. 2014-073925 Japanese Unexamined Patent Publication No. 06-21158 International Publication No. 2001/057293 Japanese Unexamined Patent Publication No. 2009-161416 Japanese Unexamined Patent Publication No. 2000-344592 Japanese Unexamined Patent Publication No. 2002-201090 Japanese Unexamined Patent Publication No. 2013-193897 Japanese Unexamined Patent Publication No. 2014-0433386

Patent Documents 8 and 9 disclose techniques for developing this effective method and further enhancing crystal cooling. These disclose techniques for stretching a cooling cylinder forcibly cooled by a cooling medium having a cooling auxiliary cylinder fitted inside from the ceiling portion toward the surface of the raw material melt. This is a technique with a very good crystal cooling effect. However, although the crystal cooling capacity is very excellent, as shown in the claims and examples of Patent Document 9, the crystal collapses due to the internal stress of the crystal due to the strengthening of cooling, and the melt surface (hereinafter referred to as “hot water”). There has been a problem that solidification occurs due to cooling of the "surface" or "liquid surface", and the single crystal undergoes dislocation. That is, even if the crystal growth rate is increased, there are problems in terms of safety and operation.

The present invention has been made to solve the above-mentioned problems, and it is possible to safely cool a single crystal as much as possible without causing the crystal to collapse or the molten metal surface to solidify and dislocations to occur frequently. It is an object of the present invention to provide a single crystal growing device that is strengthened and saves power.

In order to achieve the above object, the present invention is a CZ method single crystal growing apparatus including a rutsubo containing a raw material melt, a heater for heating the rutsubo, and a heat insulating cylinder arranged outside the heater. The single crystal pulled up from the raw material melt is arranged so as to concentrically surround the single crystal, and the cooling cylinder for cooling the single crystal and the inside of the cooling cylinder so as to concentrically surround the single crystal. A cooling auxiliary cylinder that is arranged and covers the lower part of the inner surface of the cooling cylinder, a rutsubo upper heat insulating member that is arranged above the straight body portion of the rutsubo, and an outer side of the rutsubo that is arranged outside the straight body portion of the rutsubo. The heat insulating member is arranged inside the straight body of the rutsubo and covers the outer surface of the cooling cylinder, and is placed between the heat insulating member inside the rutsubo and the bottom of the cooling cylinder above the liquid surface of the raw material melt. The cooling cylinder extends from the ceiling of the main chamber toward the liquid surface of the raw material melt, and the lower end of the cooling cylinder is from the liquid level of the raw material melt. Provided is a single crystal growing apparatus characterized in that the height is at a position of 200 mm or less.

According to such a single crystal growing device, even if the lower end of the cooling cylinder is brought close to the raw material melt, the outer surface of the cooling cylinder is covered by the heat insulating member inside the rutsubo and the bottom surface of the cooling cylinder is covered by the heat insulating member. Is not excessively cooled, and the problems of crystal collapse and solidification are solved. In addition, since the ceiling of the main chamber is covered by the crucible upper heat insulating member and the main chamber shoulder is covered by the crucible outer heat insulating member, the melt surface is not further cooled, which causes problems of increased internal stress in the crystal and dislocation. Is resolved. At this time, the heat insulating member on the outside of the crucible may have a heat insulating cylinder extending upward.
In addition, by extending the lower end of the cooling cylinder from the ceiling of the main chamber to near the surface of the molten metal, the single crystal can be prevented from being directly exposed to the ceiling and shoulders of the main chamber. can. As a result, since the object that absorbs the radiation from the single crystal is almost the cooling cylinder, it is possible to sufficiently cool the crystal without expecting the effect of absorbing the radiation heat by the main chamber. That is, even if the ceiling and shoulders of the main chamber, the outer surface of the cooling cylinder, and the bottom surface are covered with a heat insulating member, the crystal can be sufficiently cooled on the inner surface of the cooling cylinder at a closer distance, so that the growth rate of the single crystal can be improved.
Furthermore, by covering the ceiling and shoulders of the main chamber, the outer surface and bottom of the cooling cylinder with a heat insulating member, it is not possible to take extra heat from parts other than crystals, such as melts, heaters, and crucibles, which you do not want to cool. Energy saving is achieved.

The outer diameter of the cooling cylinder is preferably 140 mm or more larger than the outer diameter of the single crystal.
This is due to the following reasons.

As described above, by extending the cooling cylinder upward from the liquid surface of the raw material melt to a position of 200 mm or less, the single crystal is not directly exposed to the main chamber, so there is a demerit due to the installation of the heat insulating material. It will be resolved. Here, this value of 200 mm actually varies greatly depending on the difference between the outer diameter (diameter) of the single crystal to be grown and the outer diameter of the cooling cylinder. For example, in reality, the skeleton of the cooling cylinder has a cavity for flowing a cooling medium such as water, so that a predetermined thickness is required in the radial direction. Assuming that the thickness of the single crystal is as close to zero as possible, the single crystal may be directly exposed to the main chamber even if the distance between the lower end of the cooling cylinder and the liquid surface of the raw material melt is 200 mm or less. be.

Therefore, the position of the outer surface of the cooling cylinder should be increased by 70 mm or more in the radial direction from the position of the surface of the single crystal, that is, the outer diameter (diameter) of the cooling cylinder should be increased by 140 mm or more from the outer diameter (diameter) of the single crystal. As a result, the influence of the main chamber can be reduced and the influence of the cooling cylinder can be increased as a target for absorbing the radiation from the single crystal more reliably. Therefore, as described above, the growth rate of the single crystal can be improved without the problem of crystal collapse or dislocation without causing a decrease in the cooling capacity due to the heat insulating member.

It is preferable that the lower end of the cooling auxiliary cylinder is at the same position as or lower than the lower end of the cooling cylinder.

That is, as with the lower end of the cooling cylinder, is the lower end of the cooling auxiliary cylinder that fits inside the cooling cylinder, absorbs radiation from the single crystal, and transmits it to the cooling cylinder, which is almost the same as the cooling cylinder? Alternatively, it is preferable that the lower end of the cooling auxiliary cylinder is lower. In this case, it is preferable that the lower end of the cooling auxiliary cylinder is also at a position where the height of the raw material melt from the liquid surface is 200 mm or less.

As a result, the cooling auxiliary cylinder can efficiently transfer the heat radiated from the single crystal to the cooling cylinder, and can effectively prevent the contamination of impurities from the cooling cylinder to the single crystal.

It is preferable that the lower end of the cooling cylinder and the lower end of the cooling auxiliary cylinder are at positions where the height of the raw material melt from the liquid surface is 140 mm or less, respectively.

That is, in order to further improve the cooling capacity and eliminate the adverse effect of the heat insulating material, it is preferable to extend the lower end of the cooling cylinder closer to the liquid level (hot water level) of the raw material melt. Also, the lower end of the cooling auxiliary cylinder that fits inside the cooling cylinder, absorbs the radiation from the single crystal, and transmits it to the cooling cylinder is almost the same as the cooling cylinder, or the lower end of the cooling auxiliary cylinder. Is preferably lower.

This is because, especially when the height of these lower ends is 140 mm or less from the liquid surface of the raw material melt, a grown-in defect is formed even when a single crystal having a diameter of 300 mm is grown. This is because it is possible to set the distance in the temperature range of 1150 ° C to 1080 ° C, which is said to be, to 30 mm or less. As a result, although it depends on the growth rate, rapid cooling that easily exceeds the cooling rate of 1 ° C./min is possible, so that defect-free crystals are easily formed.

It is preferable that the lower end of the cooling cylinder and the lower end of the cooling auxiliary cylinder are at positions where the height of the raw material melt from the liquid surface is 50 mm or more, respectively.

This is because, as described above, the lower the position of these lower ends, the better, but a heat shield member is arranged between the lower ends of the cooling cylinder and the lower end of the cooling auxiliary cylinder and the liquid level of the raw material melt. It is necessary. Therefore, if each of these lower ends is located at a position of 50 mm or more from the liquid surface of the raw material melt, a sufficient space for arranging the heat shield member can be secured, and as described above, the crystal collapses during the growth of the single crystal. And the problem of dislocations is solved.

The surfaces of the crucible upper heat insulating member, the crucible outer heat insulating member, the crucible inner heat insulating member, and the heat shield member are preferably covered with a graphite material or a quartz material.

That is, as each heat insulating member, a heat insulating material that can be used at a high temperature such as carbon fiber or glass fiber is mainly used. However, the surface of such a heat insulating member is fibrous, and when it deteriorates, dust is likely to be generated, and it may react with silicon to be silicified. Therefore, as described above, if the surface of each heat insulating member is protected with a high-temperature stable substance such as a plate-shaped graphite material or a quartz material, it is possible to suppress the generation of dust and the silicification of the heat insulating member.

It is connected between at least one member of the cooling cylinder, the cooling auxiliary cylinder, the crucible inner heat insulating member, and the heat shield member, and the crucible shaft, and detects contact between these members and the raw material melt. It is preferable to further provide a safety device for the crucible.

In this technique, it is necessary to bring the cooling cylinder through which a cooling medium such as cooling water is passed close to the liquid level (hot water level) of the raw material melt. If the cooling cylinder is immersed in the melt due to malfunction or the like and the cooling water leaks out, there is a risk of steam explosion. That is, in order to avoid the danger of steam explosion, it is necessary to recognize the danger as soon as any member of the cooling cylinder, the cooling auxiliary cylinder, the crucible inner heat insulating member, and the heat insulating member comes into contact with the melt. is important.

Therefore, an electric circuit is provided between one or more of the cooling cylinder, the cooling auxiliary cylinder, the heat insulating member inside the crucible, and the heat insulating member and the crucible shaft, and the contact between these members and the liquid level of the raw material melt is provided. It is preferable to have a safety device to detect. In particular, if it is detected by a heat shield member that is likely to come into contact with the melt before the cooling cylinder, it is possible to recognize the danger before the cooling cylinder through which the cooling water passes is immersed in the melt.

Although the contact confirmation by the electric circuit is described here, the contact between the member and the raw material melt may be detected by another method. For example, if the contact or approach between the member and the raw material melt can be confirmed by some method such as contact confirmation by temperature or physical contact confirmation, the contact or approach confirmation method is not limited.

It is preferable that the cooling cylinder and the cooling auxiliary cylinder have an opening for observing the single crystal.

This is because the single crystal to be grown passes through the cooling cylinder and the cooling auxiliary cylinder, but in this technology, the cooling cylinder and the cooling auxiliary cylinder are brought close to the liquid level (hot water surface) of the raw material melt, so if it is left as it is, it is simple. It becomes difficult to observe the crystals. That is, in this technique, if a single crystal can be further observed and the diameter of the single crystal to be grown can be measured to control the diameter and temperature of the single crystal, which are necessary for producing the single crystal. , More preferred.

Therefore, as described above, if the cooling cylinder and the cooling auxiliary cylinder are provided with openings for crystal observation as needed, it is necessary to produce a single crystal through the openings for crystal observation. It can also be controlled. The size of the opening is preferably the minimum necessary size so as not to reduce the cooling effect of the single crystal.

The cooling auxiliary cylinder preferably has a cut penetrating the cooling auxiliary cylinder in the axial direction.

The outer diameter of the cooling auxiliary cylinder is approximately the same as the inner diameter of the cooling cylinder, and by fitting the cooling auxiliary cylinder into the cooling cylinder, radiation from the single crystal is efficiently absorbed and the cooling medium flowing in the cooling cylinder is used. It is preferable to eliminate the heat with. Here, if the inner diameter of the cooling cylinder and the outer diameter of the cooling auxiliary cylinder are made substantially the same, it is difficult to mount the cooling auxiliary cylinder, and the cooling auxiliary cylinder may be cracked due to the difference in thermal expansion. There is. Therefore, as described above, by making a cut (slit) in the cooling auxiliary cylinder, the cooling auxiliary cylinder can be easily attached, and the cooling auxiliary cylinder that tries to expand by receiving the heat from the single crystal adheres to the cooling auxiliary cylinder. Therefore, it is possible to efficiently transfer heat from the cooling auxiliary cylinder to the cooling cylinder.

The material of the cooling auxiliary cylinder is preferably a graphite material or a carbon composite material.

The role of the cooling auxiliary cylinder is to absorb the radiation from the single crystal by fitting it in the cooling cylinder, transmit it to the cooling cylinder, and eliminate the heat in the cooling cylinder. Therefore, the most suitable material for the cooling auxiliary cylinder is a material having high emissivity and high thermal conductivity. Graphite materials and carbon composite materials are superior in this respect. These materials are excellent in processability and can be highly purified, so that they are less contaminated with single crystals and are very useful materials.

Further, in order to achieve the above object, the present invention is a single crystal growing method using each of the above-mentioned single crystal growing devices, wherein the raw material melt is kept at an appropriate temperature by the heater and the cooling cylinder is used. The single crystal pulled up from the raw material melt is cooled, and the rutsubo is raised so as to compensate for the decrease in the liquid level of the raw material melt reduced by the pulling of the single crystal, and the lower end of the cooling cylinder and the raw material melt are raised. Provided is a method for growing a single crystal, which comprises growing the single crystal in a state where the distance from the liquid surface of the liquid is 200 mm or less.

According to such a single crystal growing method, even if the lower end of the cooling cylinder is brought close to the raw material melt, the outer surface of the cooling cylinder is covered by the heat insulating member inside the rutsubo and the bottom surface of the cooling cylinder is covered by the heat insulating member. Is not excessively cooled, and the problems of crystal collapse and solidification are solved. In addition, since the ceiling of the main chamber is covered by the crucible upper heat insulating member and the main chamber shoulder is covered by the crucible outer heat insulating member, the melt surface is not further cooled, which causes problems of increased internal stress in the crystal and dislocation. Is resolved. At this time, the heat insulating member on the outside of the crucible may have a heat insulating cylinder extending upward.
In addition, by extending the lower end of the cooling cylinder from the ceiling of the main champer to near the surface of the molten metal, the single crystal can be prevented from being directly exposed to the ceiling and shoulders of the main chamber. can. As a result, since the object that absorbs the radiation from the single crystal is almost the cooling cylinder, it is possible to sufficiently cool the crystal without expecting the effect of absorbing the radiation heat by the main chamber. That is, even if the ceiling and shoulders of the main chamber, the outer surface of the cooling cylinder, and the bottom surface are covered with a heat insulating member, the crystal can be sufficiently cooled on the inner surface of the cooling cylinder at a closer distance, so that the growth rate of the single crystal can be improved.
Furthermore, by covering the ceiling and shoulders of the main chamber, the outer surface and bottom of the cooling cylinder with a heat insulating member, it is not possible to take extra heat from parts other than crystals, such as melts, heaters, and crucibles, which you do not want to cool. Energy saving is achieved.

As described above, according to the present invention, the cooling of the single crystal is safely strengthened as much as possible and the power is saved without the crystal collapsing or the molten metal surface solidifying and causing frequent dislocations. It becomes possible to realize a certain single crystal growing device.

It is a schematic diagram of the single crystal growth apparatus of this invention. It is a schematic diagram which provided the electric circuit between one or more of a cooling cylinder, a cooling auxiliary cylinder, a crucible inner heat insulating member, a heat shielding member, and a crucible shaft. It is a schematic diagram which provided the opening for crystal observation in a cooling cylinder and a cooling auxiliary cylinder. It is a schematic diagram of the cooling auxiliary cylinder with a cut through in the axial direction. It is a figure which shows the example of the single crystal growth method of this invention. It is a schematic diagram of the single crystal growth apparatus as a comparative example.

As described in the prior art (for example, Patent Documents 8 and 9), a cooling cylinder forcibly cooled by a cooling medium is extended from the ceiling toward the surface of the raw material melt, and the inside thereof has high radiation conductivity and heat conduction. By fitting a cooling auxiliary cylinder with a high rate, a very high crystal cooling capacity can be obtained. However, this alone has the problem that the crystal collapses or the single crystal undergoes dislocation, and even if the growth rate is improved by quenching, there is a decrease in productivity due to collapse or dislocation, which is a merit. There were few.
Therefore, the present inventors first have a cooling structure including a cooling cylinder extending toward the surface of the raw material melt and a cooling auxiliary cylinder, a crucible upper heat insulating member, a crucible outer heat insulating member, a crucible inner heat insulating member, and a heat shield. The combination with the heat insulating structure having a member was examined.

As described in Patent Document 2 of the prior art, arranging such a heat insulating member in the furnace hinders cooling by the water-cooled chamber, particularly the ceiling of the main chamber, and alleviates the temperature gradient in the furnace. Therefore, if the main point is to enhance the crystal cooling, it is usually impossible to adopt the heat insulating structure in the cooling structure. However, the present inventors can maintain the heat retention of the melt by intentionally using the upper heat insulating member, the rutsubo outer heat insulating member, the rutsubo inner heat insulating member, and the heat insulating member in the cooling structure based on the idea of reversal. It is possible, and it may be possible to solve the problem of crystal collapse and especially the dislocation of single crystals due to solidification of the melt when the cooling cylinder is stretched to the melt side and only cooling is strengthened. I came to a conclusion.

Therefore, when the above-mentioned cooling structure is combined with the above-mentioned heat insulating structure including an upper heat insulating member, a crucible outer heat insulating member, a crucible inner heat insulating member, and a heat insulating member, there is a problem of crystal collapse and dislocation. We investigated the conditions under which it was possible to improve the growth rate of the single crystal by strengthening the cooling capacity of the single crystal pulled up from the raw material melt.

As a result of diligent studies on the above conditions, the present inventors maintain a state in which the lower end of the cooling cylinder is at a position of 200 mm or less from the liquid surface (hot water surface) of the raw material melt during the growth of the single crystal. Therefore, it was found that the growth rate of a single crystal can be improved without the crystals collapsing or the surface of the molten metal solidifying and causing frequent dislocations.

That is, even if the lower end of the cooling cylinder is brought close to the raw material melt as described above, the outer surface of the cooling cylinder is covered by the heat insulating member inside the crucible, and the bottom surface of the cooling cylinder is covered by the heat insulating member, so that the melt surface is excessively cooled. The problem of crystal collapse and solidification is solved. In addition, since the ceiling of the main chamber is covered by the crucible upper heat insulating member and the main chamber shoulder is covered by the crucible outer heat insulating member, the melt surface is not further cooled, which causes problems of increased internal stress in the crystal and dislocation. Is resolved. Further, the problem that the heat of the single crystal pulled up by the upper heat insulating member, the crucible outer heat insulating member, and the crucible inner heat insulating member is difficult to radiate to the ceiling portion of the main chamber is a problem that the lower end of the cooling cylinder is the ceiling portion as described above. This is solved by stretching the raw material melt close to the surface of the molten metal so that the single crystal is not directly exposed to the ceiling of the main chamber. As a result, since the object that absorbs the radiation from the single crystal is almost the cooling cylinder, it is possible to sufficiently cool the crystal without expecting the effect of absorbing the radiation heat by the main chamber. That is, even if the ceiling and shoulders of the main chamber, the outer surface of the cooling cylinder, and the bottom surface are covered with a heat insulating member, the crystal can be sufficiently cooled on the inner surface of the cooling cylinder at a closer distance, so that the growth rate of the single crystal can be improved.

That is, the present inventors have a problem that the cooling in the main chamber due to the arrangement of the heat insulating member is hindered by further strengthening the direction of extending the cooling cylinder, which worsens the crystal collapse and dislocation. At the same time, the problem of worsening crystal collapse and dislocation by extending the cooling cylinder is solved by arranging a heat shield member to alleviate the temperature gradient in the furnace and improve the heat retention of the melt. I came up with that. In addition, the present inventors have concluded that by combining these technologies, it is possible not only to improve productivity but also to reduce power intensity by energy saving.

That is, the present invention is a CZ method single crystal growing apparatus including a rutsubo containing a raw material melt, a heater for heating the rutsubo, and a heat insulating cylinder arranged outside the heater, and the raw material melt. A cooling cylinder that is arranged so as to concentrically surround the single crystal pulled up from the above, and a cooling cylinder that is arranged inside the cooling cylinder so as to concentrically surround the single crystal. A cooling auxiliary cylinder that covers the lower part of the inner surface of the rutsubo, a rutsubo upper heat insulating member arranged above the straight body portion of the rutsubo, a rutsubo outer heat insulating member arranged outside the straight body portion of the rutsubo, and the rutsubo. A heat shield member arranged inside the straight body portion of the cooling cylinder and covering the outer surface of the cooling cylinder, and a heat shield member arranged above the liquid surface of the raw material melt and between the bottom portion of the cooling cylinder. The cooling cylinder extends from the ceiling of the main chamber toward the liquid surface of the raw material melt, and the lower end of the cooling cylinder has a height of 200 mm or less from the liquid surface of the raw material melt. It is a single crystal growing device characterized by being in a position.

As described above, from the viewpoint of improving productivity, the cooling structure and the heat insulating structure are seemingly incompatible techniques, but they are described as "during the growth of a single crystal, the lower end of the cooling cylinder is from the liquid surface of the raw material melt. By combining under the condition of "keeping the state at a position of 200 mm or less", the points that were considered to be mutual drawbacks (increased internal stress of crystal, occurrence of melt solidification, decrease in growth rate) are complemented, and at the same time. It can be resolved. In addition, by combining the cooling structure and the heat insulating structure, mutual merits (improvement of productivity by improving the growth rate, improvement of productivity by preventing crystal collapse and dislocation) can be enjoyed and further strengthened. It has become possible to meet (reduction of power intensity by energy saving).

Although the lower end of the cooling cylinder is described above here, the lower end of the cooling auxiliary cylinder that is fitted inside the cooling cylinder to absorb radiation from a single crystal and transmit it to the cooling cylinder is almost the same as the cooling cylinder. Or, it is preferable that the lower end of the cooling auxiliary cylinder is lower. In this case, it is preferable that the lower end of the cooling auxiliary cylinder is also at a position where the height of the raw material melt from the liquid surface is 200 mm or less.

Hereinafter, embodiments of the present invention will be specifically described with reference to the accompanying drawings, but the present invention is not limited thereto.

FIG. 1 is a schematic view of the single crystal growing apparatus of the present invention.
A quartz crucible 5 held by a graphite crucible 6 is installed in the main chamber 1 of the single crystal growing apparatus, and the graphite crucible 6 is supported by a crucible shaft (support shaft) 18 that rotates at the center of the bottom and moves up and down. Above the main chamber 1, a pull chamber 2 provided with an opening door for taking out a single crystal (for example, silicon single crystal) 3 pulled up from the raw material melt (for example, silicon melt) 4 is provided.

An atmosphere gas (for example, Ar gas) introduction pipe 9 is provided above the pull chamber 2, and an exhaust gas pipe 8 for discharging the introduced atmosphere gas is provided at the bottom of the main chamber 1. Further, a graphite heater 7 for keeping the raw material melt 4 at an appropriate temperature is installed on the outer periphery of the graphite crucible 6. Then, while introducing the atmospheric gas from the introduction pipe 9, the seed crystal 19 is immersed in the raw material melt 4, and the pulling wire 20 is wound while rotating to pull up the single crystal 3.

In such a single crystal growing apparatus, the graphite crucible 6 and the quartz crucible 5 can rise / fall in the direction of the crystal growth axis via the crucible shaft 18, and the raw material melt 4 crystallizes and decreases during crystal growth. It rises to make up for the drop in the liquid level. Here, the heater outer heat insulating member 13, the crucible lower heat insulating member 14, the crucible upper heat insulating member 15, and the crucible outer heat insulating member 16 surround the graphite crucible 6 and the quartz crucible 5, and the raw material melt 4 melted by the graphite heater 7 Prevents heat loss.

Further, in order to improve the growth rate of the single crystal 3, it is necessary to rapidly cool the single crystal 3, and a cooling cylinder 10 is provided for that purpose. The cooling cylinder 10 is made of metal, for example, and coaxially surrounds the pulled-up single crystal 3. Further, the skeleton portion of the cooling cylinder 10 has a hollow inside, and a cooling medium such as water flows through the hollow. The cooling cylinder 10 extends from the ceiling portion T of the main chamber 1 toward the surface of the raw material melt 4, and the outer diameter of the cooling cylinder 10 is 140 mm or more larger than the outer diameter (diameter) of the single crystal 3 to be pulled up. Is preferable. Further, the lower end of the cooling cylinder 10 is located at a position where the height D of the raw material melt 4 from the liquid surface (hot water surface) is within a range of 200 mm or less, more preferably 50 mm or more and 140 mm or less.

The cooling auxiliary cylinder 11 is fitted inside the cooling cylinder 10. The role of the cooling auxiliary cylinder 11 is to absorb the radiation from the pulled-up single crystal 3 and transmit it to the cooling cylinder 10, and to prevent contamination of the pulled-up single crystal 3. Therefore, the cooling auxiliary cylinder 11 is made of, for example, a material having high radiation coefficient and high thermal conductivity and less contamination to the single crystal 3, such as a graphite material and a carbon composite material, and the inner surface of the cooling cylinder 10 is formed. It is preferable that it covers from the central portion to the lower portion of the cooling cylinder and is in close contact with the inner surface of the cooling cylinder 10. However, the range in which the cooling auxiliary cylinder 11 covers the inner surface of the cooling cylinder 10 is not limited to this, and at least the lower portion of the cooling cylinder 10 may be covered.

The lower end of the cooling auxiliary cylinder 11 is, for example, at the same position as or lower than the lower end of the cooling cylinder 10. In the figure, the lower end of the cooling cylinder 10 and the lower end of the cooling auxiliary cylinder 11 are drawn as the same position. Therefore, the lower end of the cooling auxiliary cylinder 11 is also located at a position where the height D of the raw material melt 4 from the liquid surface (hot water surface) is within the range of 200 mm or less, more preferably 50 mm or more and 140 mm or less. Is preferable.

The heat shield member 12 and the crucible inner heat insulating member 17 are provided to prevent heat loss by the cooling cylinder 10 and the cooling auxiliary cylinder 11 and to prevent cooling of the molten metal surface and the crucible. Therefore, the heat shield member 12 covers the lower end of the cooling cylinder 10, and the crucible inner heat insulating member 17 surrounds the outer surface of the cooling cylinder 10. That is, the cooling cylinder 10 is sandwiched between the cooling auxiliary cylinder 11 and the crucible inner heat insulating member 17. Further, the crucible upper heat insulating member 15 and the crucible outer heat insulating member 16 are provided to prevent heat loss due to the ceiling portion T and shoulder portion K of the main chamber and to prevent cooling of the hot water surface, the crucible, and the heater. Further, the space S formed by the crucible upper heat insulating member 15, the crucible outer heat insulating member 16, and the crucible inner heat insulating member 17 is used to raise / lower the graphite crucible 6 and the quartz crucible 5 in the crystal growth axis direction. This is a space for accommodating the straight body portion X of the 6 and the quartz crucible 5.

The heat shield member 12, the heater outer heat insulating member 13, the crucible lower heat insulating member 14, the crucible upper heat insulating member 15, the crucible outer heat insulating member 16, and the crucible inner heat insulating member 17 are, for example, heat insulating materials such as carbon fiber and glass fiber. A material having high heat insulating properties such as crucible and CC material can be used. It is preferable that the surface of these heat insulating materials is covered with a substance stable at high temperature such as graphite material and quartz material.

FIG. 2 is a schematic view in which an electric circuit is provided between any one or more of a cooling cylinder, a cooling auxiliary cylinder, a crucible inner heat insulating member, and a heat shield member, and a crucible shaft.

The single crystal growing apparatus of FIG. 1 differs from the single crystal growing apparatus of FIG. 1 in that at least one member of the cooling cylinder 10, the cooling auxiliary cylinder 11, the crucible inner heat insulating member 17, and the heat shield member 12, and the crucible shaft 18. A safety device 21 is connected to the safety device 21, and the safety device 21 detects the presence or absence of contact between these members and the raw material melt 4.

In the figure, the safety device 21 is connected between the cooling cylinder 10 and the crucible shaft 18. Since the other components are the same as those in FIG. 1, the detailed description thereof will be omitted by assigning the same reference numerals as those in FIG.

By adding the safety device 21 in this way, for example, it is detected whether or not the heat shield member 12 has come into contact with the raw material melt 4 due to a malfunction or the like, and if the heat shield member 12 has come into contact with the raw material melt 4. When this is detected, the single crystal growing operation is immediately stopped (the single crystal growing device is stopped), and the cooling cylinder 10 can be prevented from being immersed in the raw material melt 4. That is, it is possible to prevent the cooling cylinder 10 from being melted by the raw material melt 4 and the cooling medium (for example, water) leaking from the cooling cylinder 10 to cause a steam explosion.

As described above, according to this example, it is possible to realize a single crystal growing apparatus capable of safely cooling a single crystal without problems of crystal collapse and dislocation.

FIG. 3 is a schematic view in which an opening for crystal observation is provided in the cooling cylinder and the cooling auxiliary cylinder.
The cooling cylinder 10 and the cooling auxiliary cylinder 11 correspond to the cooling cylinder 10 and the cooling auxiliary cylinder 11 of FIG. The cooling cylinder 10 and the cooling auxiliary cylinder 11 coaxially surround the single crystal 3. That is, the single crystal 3, the cooling cylinder 10, and the cooling auxiliary cylinder 11 are arranged around the axis AX.

The cooling cylinder 10 and the cooling auxiliary cylinder 11 have an opening OP for observing the single crystal 3. The opening OP is provided at the lower part of the cooling cylinder 10 and the cooling auxiliary cylinder 11, but is not limited to this. Further, the number of openings OP is not limited to one, and may be plural.

According to this example, since the single crystal 3 pulled up through the opening OP for crystal observation can be observed, the control necessary for producing the single crystal 3 can be performed. The size of the opening is preferably the minimum necessary size so as not to reduce the cooling effect of the single crystal 3.

FIG. 4 is a schematic view of a cooling auxiliary cylinder having a cut penetrating in the axial direction.
The cooling auxiliary cylinder 11 corresponds to the cooling auxiliary cylinder 11 of FIG. The cooling auxiliary cylinder 11 has a cut (slit) SL penetrating the cooling auxiliary cylinder 11 in the axial direction (direction parallel to the axis AX).

The cut SL has an effect of facilitating the mounting of the cooling auxiliary cylinder 11 having the outer diameter basically equal to the inner diameter of the cooling cylinder to the cooling cylinder 10. Further, during the growth of the single crystal, when the cooling auxiliary cylinder 11 receives heat from the single crystal, it tries to expand and comes into close contact with the cooling cylinder 10, so that heat is efficiently transferred from the cooling auxiliary cylinder 11 to the cooling cylinder 10. It becomes possible.

FIG. 5 shows an example of the single crystal growing method of the present invention.
This single crystal growth method is carried out using the single crystal growth apparatus of FIG. If step ST2, which will be described later, is omitted, the single crystal growing method of the present invention can be executed by the single crystal growing device of FIG. Further, in the following description, the reference numerals attached to each component correspond to the reference numerals of the components shown in FIG. 1 or FIG.

First, the graphite heater 7 keeps the raw material melt 4 at an appropriate temperature, the cooling cylinder 10 cools the single crystal 3 pulled up from the raw material melt 4, and the liquid level of the raw material melt 4 decreased by pulling up the single crystal 3. The graphite crucible 6 and the quartz crucible 5 are raised so as to make up for the falling portion of. Further, the single crystal 3 is grown in a state where the distance between the lower end of the cooling cylinder 10 and the liquid level of the raw material melt 4 is 200 mm or less (step ST1).

Next, it is confirmed whether or not the abnormality is detected by the safety device 21 (step ST2).
When an abnormality is detected by the safety device 21, the single crystal growing device is immediately stopped, and the single crystal growing operation is terminated.

On the other hand, when no abnormality is detected by the safety device 21, it is confirmed whether or not the growth of the single crystal 3 is completed (step ST3).
When the growth of the single crystal 3 is completed, the single crystal growth apparatus is stopped and this flow is terminated. If the growth of the single crystal 3 has not been completed, the process returns to step ST2, and while continuing the growth operation of the single crystal 3, it is reconfirmed whether or not the safety device 21 has detected an abnormality.

According to such a single crystal growing method, it is possible to safely perform a power-saving operation capable of enhancing the cooling capacity of the cooling cylinder 10 and improving the growth rate of the single crystal without the problem of crystal collapse or dislocation. can.

As described above, according to the present invention, the cooling of the single crystal is safely strengthened and saved as much as possible without the crystals collapsing or the molten metal surface solidifying and causing frequent dislocations. It is possible to realize a single crystal growing device that is electric power.

Hereinafter, the present invention will be described in detail with reference to examples of the present invention, but these are not intended to limit the present invention.

(Example 1)
In the single crystal growing device shown in FIG. 1, a crucible having a diameter of 32 inches (about 813 mm) is equipped, and a single crystal having a diameter of about 12 inches (about 305 mm) is grown using the magnetic field applied Czochralski method (MCZ method). bottom. At this time, the outer diameter (diameter) of the cooling cylinder 10 is made 210 mm (105 mm in radius) larger than the target diameter of the single crystal 3, and the lower end of the cooling cylinder 10 and the lower end of the cooling auxiliary cylinder 11 are the liquids of the raw material melt 4. It was set at a position 105 mm from the surface. An isotropic graphite material was used as the material of the cooling auxiliary cylinder 11, and the cooling auxiliary cylinder 11 was provided with a cut SL (FIG. 4) penetrating in the axial direction. Further, the cooling cylinder 10 and the cooling auxiliary cylinder 11 are provided with an opening OP (FIG. 3) for crystal observation.

In the CZ method, the crucibles 5 and 6 filled with the raw material melt 4 and the graphite heater 7 arranged so as to surround the crucibles 5 and 6 are used. After immersing the seed crystal 19 in the crucibles 5 and 6, the rod-shaped single crystal 3 is pulled up from the raw material melt 4. The crucibles 5 and 6 can be moved up and down in the direction of the crystal growth axis via the crucible shaft 18, so as to compensate for the decrease in the liquid level of the raw material melt 4 reduced during the crystal growth, and desired. Raise the crucibles 5 and 6 so that they are at the hot water surface position.

Defect-free crystals were grown using this pulling machine. In a defect-free crystal, the growth rate margin at which defects can be obtained is very narrow, so that it is easy to determine an appropriate growth rate. Therefore, using this pulling machine, the crystal growth rate was determined so that a completely defect-free crystal could be obtained. Then, a sample was cut out from the grown single crystal 3 and it was confirmed by selective etching whether or not it became a defect-free crystal.

As a result, it was found that the crystal growth rate at which a completely defect-free crystal can be obtained is about 17% faster than the growth rate shown in Comparative Example 1 described later. Furthermore, when five single crystals were continuously grown using this apparatus, dislocations occurred only once, and the dislocation rate was 0.2 times / piece, which will be compared later. A very good value was obtained as compared with the dislocation rate shown in Example 2.

(Comparative Example 1)
The single crystal 103 was grown using the single crystal growing apparatus shown in FIG.
Here, 101, 102, 103, 104, 105, 106, 107, 108, 109, 110, 111, 112, 113, 114, 115, 116, 117, and 118 are the main chamber 1 and pull in FIG. 1, respectively. Chamber 2, single crystal 3, raw material melt 4, quartz crucible 5, graphite crucible 6, graphite heater 7, exhaust gas pipe 8, introduction pipe 9, cooling cylinder 10, cooling auxiliary cylinder 11, heat shield member 12, heater outer heat insulating member 13. Corresponds to the crucible lower heat insulating member 14, the crucible upper heat insulating member 15, the crucible outer heat insulating member 16, the crucible inner heat insulating member 17, and the crucible shaft 18.

In Comparative Example 1, the length of the cooling cylinder 110 is set short (the position of the lower end is 350 mm from the liquid surface of the raw material melt 104), and the cooling auxiliary cylinder 111 inscribed in the cooling cylinder 110 is downward. By setting the stretching (the position of the lower end is 230 mm from the liquid level of the raw material melt 104), the cooling cylinder and the cooling auxiliary cylinder are stretched close to the molten metal surface to enhance the cooling of the single crystal 103. Grow defect-free crystals under the same conditions as in the above-mentioned example, and determine the growth rate of the single crystal 103 at that time.

As a result, the crystal growth rate was 17% slower than that of Example 1. That is, in the above-mentioned Example 1 according to the present invention, it was confirmed that the defect-free crystal growth rate was improved by stretching the cooling cylinder and the cooling auxiliary cylinder toward the liquid surface of the raw material melt. ..

(Comparative Example 2)
The single crystal 3 was grown using the single crystal growing apparatus shown in FIG.
However, in Comparative Example 2, the same method as in Example 1 is used except that the crucible upper heat insulating member 15, the crucible outer heat insulating member 16, and the crucible inner heat insulating member 17 are removed from the single crystal growing apparatus of FIG. , A defect-free crystal was grown.

As a result, dislocations occurred, and it was not possible to obtain defect-free crystals having the same length as in Example 1. Further, as a result of trial production of two single crystals 3, the dislocation rate was 1.5 times / line, which was significantly increased as compared with Example 1, which was higher than the productivity improvement due to the improvement of the growth rate. The result was that the decrease in productivity due to dislocations was greater. Further, the electric power required for crystal growth was also increased by about 15% as compared with Example 1, and the electric power per unit product quantity (electric power intensity unit) was much higher than that of Comparative Example 1.

As can be seen from the above results, in the present invention, in the structure in which the cooling cylinder 10 and the cooling auxiliary cylinder 11 are extended from the ceiling of the main chamber 1 to near the liquid level of the raw material melt 4, the upper heat insulating member 15 and the rutsubo are further extended. It was confirmed that by providing the outer heat insulating member 16 and the inner heat insulating member 17 of the rutsubo, dislocation formation can be greatly suppressed and energy saving can be achieved.

As described above, according to the present invention, the cooling of the single crystal can be safely strengthened as much as possible without the crystals collapsing or the molten metal surface solidifying and causing frequent dislocations. It is possible to realize a single crystal growing device that saves power.

The present invention is not limited to the above embodiment. The above-described embodiment is an example, and any one having substantially the same structure as the technical idea described in the claims of the present invention and having the same effect and effect is the present invention. Is included in the technical scope of.

1 ... Main chamber, 2 ... Pull chamber, 3 ... Single crystal, 4 ... Raw material melt, 5 ... Quartz crucible, 6 ... Graphite crucible, 7 ... Graphite heater, 8 ... Exhaust pipe, 9 ... Introduction pipe, 10 ... Cooling cylinder , 11 ... Cooling auxiliary cylinder, 12 ... Heat shield member, 13 ... Heater outer heat insulating member, 14 ... Crucible lower heat insulating member, 15 ... Crucible upper heat insulating member, 16 ... Crucible outer heat insulating member, 17 ... Crucible inner heat insulating member, 18 ... Crucible shaft, 19 ... Seed crystal, 20 ... Pull-up wire, 21 ... Safety device, D ... Distance between the lower end of the cooling cylinder and the liquid level of the raw material melt, S ... Space where the quartz crucible and the straight body of the graphite crucible fit. T ... The ceiling of the main chamber.

Claims (10)

A CZ method single crystal growing device including a crucible containing a raw material melt, a heater for heating the crucible, and a heat insulating cylinder arranged outside the heater.
A cooling cylinder that is arranged so as to concentrically surround the single crystal pulled up from the raw material melt and cools the single crystal.
A cooling auxiliary cylinder, which is arranged inside the cooling cylinder so as to concentrically surround the single crystal and covers the lower part of the inner surface of the cooling cylinder,
The crucible upper heat insulating member arranged above the straight body of the crucible,
The crucible outer heat insulating member arranged outside the straight body of the crucible,
A heat insulating member inside the crucible, which is arranged inside the straight body of the crucible and covers the outer surface of the cooling cylinder.
It is provided with a heat shield member which is arranged above the liquid surface of the raw material melt and between the bottom of the cooling cylinder and covers the bottom of the cooling cylinder.
The cooling cylinder extends from the ceiling of the main chamber toward the liquid level of the raw material melt, and the lower end of the cooling cylinder is at a position where the height of the raw material melt from the liquid level is 50 mm or more and 200 mm or less. In
A single crystal growing apparatus characterized in that the lower end of the cooling auxiliary cylinder is at a position where the height of the raw material melt from the liquid surface is 50 mm or more. The single crystal growing apparatus according to claim 1, wherein the outer diameter of the cooling cylinder is 140 mm or more larger than the outer diameter of the single crystal. The single crystal growing apparatus according to claim 1 or 2, wherein the lower end of the cooling auxiliary cylinder is at the same position as or lower than the lower end of the cooling cylinder. One of claims 1 to 3, wherein the lower end of the cooling cylinder and the lower end of the cooling auxiliary cylinder are located at positions where the height of the raw material melt from the liquid surface is 140 mm or less, respectively. The single crystal growing apparatus according to the above. Claims 1 to 4, wherein the surfaces of the crucible upper heat insulating member, the crucible outer heat insulating member, the crucible inner heat insulating member, and the heat insulating member are covered with a graphite material or a quartz material. The single crystal growing apparatus according to any one of the following items. At least one member of the cooling cylinder, the cooling auxiliary cylinder, the inner heat insulating member of the crucible, and the heat shield member is connected between the crucible shaft for raising and lowering the crucible, and these members and the raw material are fused. The single crystal growing device according to any one of claims 1 to 5, further comprising a safety device for detecting contact with a liquid. The single crystal growing apparatus according to any one of claims 1 to 6, wherein the cooling cylinder and the cooling auxiliary cylinder have an opening for observing the single crystal. The single crystal growing apparatus according to any one of claims 1 to 7, wherein the cooling auxiliary cylinder has a cut penetrating the cooling auxiliary cylinder in the axial direction. The single crystal growing apparatus according to any one of claims 1 to 8, wherein the material of the cooling auxiliary cylinder is a graphite material or a carbon composite material. A single crystal growing method using the single crystal growing device according to any one of claims 1 to 9.
The single crystal pulled up from the raw material melt is cooled by the cooling cylinder while keeping the raw material melt at an appropriate temperature by the heater.
The crucible is raised so as to compensate for the decrease in the liquid level of the raw material melt reduced by pulling up the single crystal.
A method for growing a single crystal, wherein the single crystal is grown while the distance between the lower end of the cooling cylinder and the liquid level of the raw material melt is maintained at 200 mm or less.

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